Rotary electrical connectors are used in a variety of applications where one part must mechanically rotate with respect to another part while retaining an electrical connection between the two. Where the required extent of rotation is small, typically less than one complete revolution, hardwired electrical connections can be used. However, hardwired connections can be difficult and expensive to make, especially where such connections must be made at remote locations or in confined spaces.
For larger required rotations, on the order of several revolutions, wraparound wire arrangements are available. In other instances, the connector must permit an arbitrarily large extent of rotation. In such a connector, electrical connection must be maintained, and the mode of connection cannot hinder the rotational movement. For these applications, the most common type of connector is a slip ring system. A plurality of slip rings in side-by-side arrangement extend along the length of a rotating shaft. Stationary brushes make contact to the individual slip rings. Unfortunately, such systems are typically expensive, due to the number of parts, and can be too bulky for some applications.
Some of the foregoing problems are addressed by Mohi Sobhani in his patent entitled "Rotary Electrical Connector," U.S. Pat. No. 5,588,843. That patent describes an electrical connector that includes two planar connector members positioned perpendicular to an axis of rotation and supported in rotational facing relation. One of the connector members has a set of concentric tracks, and the other has a corresponding set of protrusions positioned to contact the tracks. The two connector members are urged together by a spring so that the concentric tracts remain in electrical contact with the protrusions. A second patent to Sobhani, U.S. Pat. No. 5,690,498, entitled "Spring Loaded Rotary Connector," teaches a similar connector in which the protrusions are replaced with dimples. Both of the foregoing Sobhani patents are incorporated herein by reference.
The Sobhani connectors work well in many applications. However, the complexity of making the protrusions or dimples increases the cost of making the connectors. Further, such connectors can be sensitive to shock, which can damage the protrusions or dimples. There is therefore a need for a more robust and less expensive means of providing rotational electrical contact.